Failed to call listener on field data cache unloading – How to solve this Elasticsearch error

Opster Team

Aug-23, Version: 6.8-8.9

Briefly, this error occurs when Elasticsearch is unable to execute a listener function during the unloading of field data cache. This could be due to insufficient memory, a bug in the listener function, or a problem with the underlying storage. To resolve this issue, you can try increasing the heap size, checking the listener function for errors, or verifying the health of your storage system. Additionally, ensure that your Elasticsearch version is up-to-date as this could be a bug that has been fixed in a newer version.

This guide will help you check for common problems that cause the log ” Failed to call listener on field data cache unloading ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: indices, cache, fielddata.

Log Context

Log “Failed to call listener on field data cache unloading” classname is
We extracted the following from Elasticsearch source code for those seeking an in-depth context :

                    notification.getRemovalReason() == RemovalNotification.RemovalReason.EVICTED;
            } catch (Exception e) {
                // load anyway since listeners should not throw exceptions
                logger.error("Failed to call listener on field data cache unloading"; e);

    public static class FieldDataWeigher implements ToLongBiFunction {


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